The present invention relates to a dust collector-equipped power cutter, and in particular to a power transmission mechanism for a portable type dust collector-equipped power cutter that includes a cutting disk and a dust-sucking fan that are driven by a prime mover.
A conventional portable type dust collector-equipped power machine of this kind, which is currently produced, is generally constituted by a main body provided with a prime mover, such as a small air-cooled two stroke internal combustion engine or an electric motor, a cutting head portion having a cutting disk that is rotated by the prime mover and having a safety cover, and a dust-sucking fan attached to the safety cover for sucking dust from the site of the cutting and discharging dust generated by the power cutter when it is operated.
In the conventional portable type dust collector-equipped power cutter of the aforementioned type, the speed of rotation of the prime mover is reduced before it is transmitted to the cutting disk, thereby to rotate the cutting disk at a lower rotational speed than the rotational speed of the prime mover, and at the same time, the reduced speed of the prime mover is taken off so as to transmit it to the dust-sucking fan, thereby to rotate the dust-sucking fan. Therefore, the speed of rotation of the dust-sucking fan tends to become slow, thus making it difficult to achieve a sufficient dust-sucking capability of the dust-sucking fan.
With a view to overcoming the problem mentioned above, the owner of the present invention has previously proposed in Japanese Patent Application No. H9-30786 (Japanese Patent Laid-Open Publication 10-225925) a dust collector-equipped power cutter which provides rotation of the dust-sucking fan thereof at high speed. In that dust collector-equipped power cutter the output shaft of a prime mover is operably connected with a centrifugal clutch having a clutch drum to which a pulley of smaller diameter as well as a pulley of larger diameter are integrally formed such that, by means of the prime mover, the cutting disk can be rotated through a combination of the aforementioned smaller pulley and a first belt at a lower speed, and at the same time, the dust-sucking fan can be rotated through a combination of the aforementioned larger pulley and a second belt at a higher speed. According to this structure, the dust-sucking fan of the dust collector-equipped power cutter rotates at a higher speed, thereby enhancing the suction force of the dust-sucking fan and hence enabling the dust generated by the operation of the cutting disk to be sufficiently sucked away from the cutting site and discharged.
However, since the rotation from the output shaft of the prime mover is individually transmitted to the cutting disk and to the dust-sucking fan through a combination of the aforementioned smaller pulley and a first belt, and through a combination of the aforementioned larger pulley and a second belt, respectively, the number of parts for the power transmitting mechanism required between the output shaft of the prime mover and the cutting disk or the dust-sucking fan is inevitably increased and hence the layout and construction of the parts is rather complicated, thus leading to an increase in manufacturing cost of the entire transmission mechanism as well as in the cost of assembling it.